Fix Code of Conduct Link in README.md (#1196)
Fix Code of Conduct Link in README.md (#1196)

Relative link was pointing to blob/master/wiki which was giving a 404.
Changed to absolute URL to keep the link working on clones and forks.
denverwilliams/linkerd,pawelprazak/linkerd,linkerd/linkerd,linkerd/linkerd,denverwilliams/linkerd,BuoyantIO/linkerd,BuoyantIO/linkerd,pawelprazak/linkerd,linkerd/linkerd,denverwilliams/linkerd,pawelprazak/linkerd,denverwilliams/linkerd